大跨度桥梁龙卷风荷载物理模拟的关键相似参数
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摘要
为识别大跨度桥梁主梁断面在龙卷风作用下的风荷载特性及其主要影响实验参数,在龙卷风风场特性模拟的基础上,基于龙卷风模拟装置和刚体模型测压实验方法,对流线型扁平钢箱主梁表面风压分布、断面三分力系数等风荷载特性进行了识别,并讨论了涡流比、高宽比等龙卷风相似参数对风荷载识别结果的影响。结果表明,桥梁主梁在模拟龙卷风作用下的风荷载特性与常规边界层风洞实验结果明显不同。高宽比对风荷载特性的影响程度远大于其对风场特性的影响。不同涡流比下,高宽比对风荷载特性的影响程度不同。高宽比和涡流比是影响桥梁主梁龙卷风荷载的关键相似参数。风荷载模拟结果及其关键相似参数的影响规律将为桥梁抗龙卷风设计提供基础气动参数数据。
In order to identify tornado-induced wind load characteristics of long-span bridges and the main influencing experimental factors,surface pressure distributions over the deck as well as aerodynamic coefficients were determined through rigid model wind pressure measurements in a tornado vortex simulator.In the experiments,similarity parameters including swirl ratio and aspect ratio were considered.Significant differences are observed between experimental wind loads in the tornado vortex simulator and in the conventional boundary layer wind tunnel.The influence of aspect ratio on the tornado-induced wind loads is much greater than that on the tornadic wind fields,and the degree of the influence is dependent on swirl ratio.According to the results,aspect ratio and swirl ratio are two key similarity parameters in the determination of tornado-induced wind loads on long-span bridges.The experimental findings can provide basic aerodynamic coefficients for tornado-resistant designs on long-span bridges.
In order to identify tornado-induced wind load characteristics of long-span bridges and the main influencing experimental factors,surface pressure distributions over the deck as well as aerodynamic coefficients were determined through rigid model wind pressure measurements in a tornado vortex simulator.In the experiments,similarity parameters including swirl ratio and aspect ratio were considered.Significant differences are observed between experimental wind loads in the tornado vortex simulator and in the conventional boundary layer wind tunnel.The influence of aspect ratio on the tornado-induced wind loads is much greater than that on the tornadic wind fields,and the degree of the influence is dependent on swirl ratio.According to the results,aspect ratio and swirl ratio are two key similarity parameters in the determination of tornado-induced wind loads on long-span bridges.The experimental findings can provide basic aerodynamic coefficients for tornado-resistant designs on long-span bridges.
引文
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[2]YANG Q,GAO R,BAI F,et al.Damage to buildings and structures due to recent devastating wind hazards in East Asia[J].Natural Hazards,2018,92(3):1321-1353.
[3]范雯杰,俞小鼎.中国龙卷的时空分布特征[J].气象,2015,41(7):793-805.FAN W J,YU X D.Characteristics of spatial-temporal distribution of tornadoes in China[J].Meteorological Monthly,2015,41(7):793-805.(in Chinese)
[4]TAMURA Y.Wind-induced damage to buildings and disaster risk reduction[C]//Proc.of 7th Asia-Pacific Conference on Wind Engineering.Taipei,2009.
[5]SENGUPTA A,HAAN F L,SARKAR P P,et al.Transient loads on buildings in microburst and tornado winds[J].Journal of Wind Engineering&Industrial Aerodynamics,2008,96(10):2173-2187.
[6]SABAREESH G R,MATSUI M,TAMURA Y.Characteristics of internal pressures and net local roof wind forces on a building exposed to a tornado-like vortex[J].Journal of Wind Engineering and Industrial Aerodynamics,2013,112:52-57.
[7]CASE J,SARKAR P P,SRITHARAN S.Effect of low-rise building geometry on tornado-induced loads[J].Journal of Wind Engineering&Industrial Aerodynamics,2014,133:124-134.
[8]WANG J,CAO S,PANG,W,et al.Experimental study on tornado-induced wind pressures on a cubic building with openings[J].Journal of Structural Engineering,2018,144(2):04017206.
[9]YANG Z,SARKAR P,HU H.An experimental study of a high-rise building model in tornado-like winds[J].Journal of Fluids&Structures,2011,27(4):471-486.
[10]CAO S,WANG J,CAO J,et al.Experimental study of wind pressures acting on a cooling tower exposed to stationary tornado-like vortices[J].Journal of Wind Engineering and Industrial Aerodynamics,2015,145:75-86.
[11]WANG J,CAO S,PANG W,et al.Wind-load characteristics of a cooling tower exposed to a translating tornado-like vortex[J].Journal of Wind Engineering and Industrial Aerodynamics,2016,158:26-36.
[12]LIU Z,ZHANG C,ISHIHARA T.Numerical study of the wind loads on a cooling tower by a stationary tornado-like vortex through LES[J].Journal of Fluids&Structures,2018,81:656-672.
[13]陈艾荣,刘志文,周志勇.大跨径斜拉桥在龙卷风作用下的响应分析[J].同济大学学报(自然科学版),2005,33(5):569-574.CHEN A,LIU Z,ZHOU Z.Tornado effects on large span cable-stayed bridges[J].Journal of Tongji University(Natural Science),2005,33(5):569-574.(In Chinese)
[14]CAO B,SARKAR P P.Numerical simulation of dynamic response of a long-span bridge to assess its vulnerability to nonsynoptic wind[J].Engineering Structures,2015,84:67-75.
[15]HAO J,WU T.Tornado-induced effects on aerostatic and aeroelastic behaviors of long-span bridge[C]//Proc.of the 2016World Congress on Advances in Civil Environmental&Materials Research.Jeju,2016.
[16]HAAN JR F L,SARKAR P P,GALLUS W A.Design,construction and performance of a large tornado simulator for wind engineering applications[J].Engineering Structures,2008,30(4):1146-1159.
[17]REFAN M,HANGAN H,WURMAN J.Reproducing tornadoes in laboratory using proper scaling[J].Journal of Wind Engineering and Industrial Aerodynamics,2014,135:136-148.
[18]CHURCH C R,SNOW J T,BAKER G L,et al.Characteristics of tornado-like vortices as function of swirl ratio:A laboratory investigation[J].Journal of the Atmospheric Sciences,1979,36:1755-1776.
[19]王锦,周强,曹曙阳,等.龙卷风风场的试验模拟[J].同济大学学报(自然科学版),2014,42(11):1654-1659.WANG J,ZHOU Q,CAO S,et al.Physical study on tornadolike flow based on Tornado Vortex Simulator[J].Journal of Tongji University(Natural Science),2014,42(11):1654-1659.(In Chinese)